ECs can most certainly help in admissions, particularly if you're talented and devoted to whatever it is.
This is commonly stated, of course. See idad in #12, for example. But curiously, there is little proof it actually matters in practice!
Worse, it is hard to know what "talented and devoted" means, especially in comparison to the rest of the talent pool.
Some parents think a kid who is first violin in the HS orchestra is a standout. At some schools, they're a dime a dozen in the applicant pool.
Further, I suspect, based strictly on anecdotal evidence, that there are few academically high performing kids that are not at least "local level standouts" in something.
But enough debate. If you feel, in the absence of any real info, that your ECs are going to matter, go for it. You'll have lots of company. But I would like to see kids that do an EC because they find the EC rewarding in its own right, not because they're building a resume. Then, it does not matter anyway.